<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>AJAX POST 请求</title>
    <style>
        #result{
            width: 200px;
            height: 100px;
            border: 1px solid #990033;
        }
    </style>
</head>
<body>
    <div id="result"></div>
    <script>
        // 获取元素对象
        const result = document.getElementById('result');
        // 绑定事件
        result.addEventListener('mouseover',function(){
            // 1.创建对象
            const xhr = new XMLHttpRequest();
            // 2.初始话  设置类型与url
            xhr.open('POST','http://127.0.0.1:8000/server');
            // 3.发送
            // xhr.send('a=100&b=200&c=300');
            xhr.send('a:100&b:200&c:300');

            // 4.事件绑定
            xhr.onreadystatechange = function(){
                // 判断
                if(xhr.readyState === 4){
                    if(xhr.status >= 200 && xhr.status<300){
                        // 处理返回服务端的结果
                        result.innerHTML = xhr.response;
                    }
                }
            }
        })
    </script>
</body>
</html>